Here's a look at the Russian spy plane that's flying close to US-South Korea military exercises

Russia performed an unusual mission last week, sending jets, nuclear bombers and a surveillance plane around the Korean Peninsula while the US and South Korea conducted joint military exercises.

Su-35S fighter jets, Tupolev-95MS bombers and an A-50U early warning and control aircraft flew over the Pacific Ocean, the Sea of Japan, the Yellow Sea and the East China Sea.

Seoul has accused Russian aircraft of violating its air defence identification zone, but also said their air space had not been violated. South Korea and Japan fighters eventually intercepted them.

Prior to the mission, Moscow had spoken out against the joint US and South Korea military exercises, arguing that they do “not help reduce tensions on the Korean peninsula,” Russian foreign ministry spokeswoman Maria Zakharova said.

But the US and South Korea say that the annual Ulchi-Freedom Guardian drills, which Pyongyang has also accused of raising tensions, are defensive in nature.

The drills, which include 17,500 US troops and 50,000 South Korean troops, are “computer simulated defensive exercise designed to enhance readiness, protect the region and maintain stability on the Korean peninsula.”

The surveillance plane that Moscow sent near the drills, the A-50U, is a “giant flying data processing center” used to detect “and [track] a number of aerial (fighter jets, bombers, ballistic and cruise missiles), ground (tank columns) and surface (above-water vessels) targets,” according to Sputnik, a Russian state-owned media outlet.

It also informs “command centres about the developments in the air and sea, and directing fighter and strike aviation.”

Check it out below.

The A-50U made its first flight in 2011, and is the most recent upgrade of the original A-50U, which entered Russia's service in 1989.

Russian Ministry of Defense

Source: Sputnik.

Based off the Ilyushin Il-76 airframe, the A-50U can track surface targets up to 186 miles and aerial targets up to 373 miles.

The plane also functions as a control center, able to manage 10-12 fighter jets at a time.

The A-50U holds a crew of about 15: 'Two pilots, a navigator, an on-board engineer and a communications specialist operate the aircraft ... three tracking operators, three guidance navigators and three engineers.'